Generally, a ski boot in plastic material essentially comprises:
a shell designed to receive the foot;
a front spoiler designed to enclose the leg, and being pivotally mounted on the shell;
means of clamping the shell and spoiler on the foot and leg.
A number of clamping systems have been proposed up to now. A first one uses a level combined with a closed loop forming a clamping member engaging into hooks (see applicant's U.S. Pat. No. 4,150,500). This solution, although well known, has the disadvantage of requiring closing forces which increase as one moves away from the rotation axis of the lever with respect to its base.
In a second system, the clamping member is constituted by a rack buckle essentially composed of a lever, a serrated strap forming fastening member and a catch designed to cooperate with the teeth of the strap (see for example U.S. Pat. No. 3,662,435). In practice with this latest system, which is also commercialized with success, the lever is associated to the strap by a toggle joint system which permits to reduce the force. Unfortunately, this solution presents considerable disadvantages, and in particular:
when the catch is constructed with releasing kinematics, any accidental shock can cause it to open;
the free end of the strap which juts out of the catch forms a projection so that, when the skier is walking, the strap end of one boot can get caught with that of the other boot;
snow can be caught under the catch, this impeding its opening;
depending on the morphology of the skier's leg and foot, the straps extend more or less out of said catch, this increasing the risks of the strap ends becoming entangled between the two feet;
finally, this system is apparent and therefore does little for the appearance of the boot.